1. Technical Field
The present invention relates generally to electrical circuits. More particularly, the present invention relates to offset cancellation for continuous-time circuits.
2. Description of the Background Art
A high speed serial interface (“HSSI”) may be used to communicate between devices in a system. Typically, it is the intention for the transmitter in such a system to transmit a digital (binary) signal having two distinctive levels, and well-defined (i.e., very steep) transitions from either of these levels to the other level. Such steep transitions are essential to transmitting data at high speed. The medium that conveys the signal from the transmitter to the receiver usually imposes losses on the signal being transmitted. These losses generally include diminished signal amplitude and reduced transition steepness.
To maintain accurate, high-speed data transmission, it is necessary for the circuitry to compensate for these losses. One compensation technique is to use what is called equalization at the receiver. Equalization circuitry is typically among the first circuitry that the incoming signal sees when it reaches the receiver. Equalization circuitry may be designed to amplify higher frequencies so as to respond strongly and rapidly to transitions detected in the received signal. This strong and rapid response is intended to restore the original steepness to these transitions, thereby making it possible for further circuitry of the receiver to correctly interpret the signal, even at the very high data rate of that signal.
It is highly desirable to improve equalizers and other continuous-time circuits for high-speed serial interfaces and other applications.